This invention relates to an imaging device, more particularly, to an imaging device employing a recording medium which carries thereon a plurality of photo and pressure sensitive microcapsules, each microcapsule containing therein a chromogenic material and a photo-curable or photo-softenable resin.
The imaging device of this type comprises, for instance, as disclosed in the U.S. Pat. No. 4399209, exposure means for exposing the recording medium to an optical image so as to form a latent image thereon corresponding to an image to be recorded, and a pressure-developing means for pressing the recording medium carrying the latent image and a separate developing medium coated with a developer which reacts to the chromogenic material, superposed one upon the other, to develop a visible image on the developing medium.
With the above imaging device, the latent image is formed on the recording medium by exposing the optical image thereon to selectively cure the photo-curable resins or soften the photo-softenable resins enveloped in the microcapsules existing on the area, to which the optical image is exposed. The latent image thus formed on the recording medium is then transferred and developed on the separate developing medium.
Transferring of the image is executed by superposing the recording medium and the developing medium one on the other and pressurizing the superposed mediums so that the unhardened or softened microcapsules on the recording medium are ruptured by the applied pressure and the chromogenic materials enveloped therin are streamed out of the ruptured microcapsules. The streamed-out chromogenic materials are reacted to the developer coated on the developing medium so as to form the visible image thereon corresponding to the above latent image.
In order to make the arrangements in the device and maintenances therefore simple and easy, the continuous form of the above recording medium, one end of which is rolled on a feed roll while the other end on a take-up roll, has been employed. On the other hand, as the developing medium, a cut-sheet form cut into pieces of the predetermined size is used.
With this continuous form recording medium, it is fed from the feed roll to the take-up roll through the exposure means and the pressure-developing means. When it passes through the exposure means, the latent image is formed thereon, and when it passes through the pressure-developing means, the latent image is transferred and developed onto the cut-sheet-form developing mediums which are successively supplied to be superposed on the corresponding areas of the continuous recording medium before it reaches the pressure-developing means.
With employing the above continuous-form recording medium, however, there arises a problem. That is, in the imaging device of the above type, the pressure-developing means usualy comprises a pair of pressure rollers adapted to be brought into and out of contact with each other.
The rollers are kept out of contact until the leading end of the developer medium is put between the rollers, and thereafter the rollers are brought into contact and start rotation for pressure developement.
With the above arrangement, however, the rollers begin rotation after they have clamped the recording medium and the developing medium between them under pressure. As a result, the leading end of the developing medium clamped by the rollers is kept under pressure for a longer time than other parts of the medium, so that even the hardened or unsoftened microcapsules on the recording medium are crushed to cause the chromagenic materials to be streamed out of them, resulting in a black line appearing on the leading end of the developing medium. Also, when terminating the pressure developing operation, it is only after completion of pressure development that the rollers stop rotation and are away from each other, so that the trailing end of the developer medium is pressurized for a longer time than other parts of the medium, again resulting in a similar black line appearing on this part.